Liquid hydrogen is a form of hydrogen that has been cooled to extremely low temperatures, turning it into a pale blue liquid. This process makes it much denser than gaseous hydrogen, allowing for easier storage and transport. Liquid hydrogen is often used as a fuel in space exploration, particularly in rockets like the Space Shuttle and Saturn V, due to its high energy content. When liquid hydrogen is combined with oxygen, it produces water as a byproduct, making it a clean fuel option. However, handling liquid hydrogen requires special equipment and safety measures because it is highly flammable and can cause severe cold burns.